FINITE(3,L)                 AIX Technical Reference                 FINITE(3,L)



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finite, logb, scalb



PURPOSE

Used in floating point calculations.

LIBRARY

Standard C Library (libm.a)

SYNTAX

#include <math.h>

int finite (x)
double x;

double logb (x)
double x;

double scalb (x, n)
double x;
int n;

DESCRIPTION

These subroutines are required for, or recommended by the IEEE standard 754 for
floating point arithmetic.

finite(x) = 1 only when -infinity < x < +infinity.
finite(x) = 0 otherwise (when |x| = infinity or x is NaN ().

logb(x) returns x exponent n, a signed integer converted to double-precision
floating point.  It is set to 1 < |x|/2**n <2 unless x=0 or |x|=infinity.

scalb(x, n) = x*(2**n) computed, for integer n, without first computing 2**n.

RELATED INFORMATION

In this book:  "floor, ceil, fmod, fabs, rint," and "math.h."












Processed November 7, 1990        FINITE(3,L)                                 1